The method disclosed in the six-page specification of preparing perindopril arginine was limited to a single sentence that generically referred to “a classical method of salification of organic chemistry”. At the time of filing, however, Servier had prepared perindopril arginine by two specific methods, the “1986 method” and the “1991 method”, the latter of which was used to prepare the perindopril arginine that formed the basis of the stability study of the patent.

Best method

In the initial Federal Court decision, the primary Judge considered that the disclosure of classical salification was “pregnant with ambiguity” and ultimately found that Servier had failed to describe the best method known to it of performing the invention as required under s 40(2)(a) of the Patents Act 1990.

In the Full Federal Court appeal, Servier relied on the lenient sufficiency requirement under the relevant Australian law, which is satisfied by a disclosure that would enable the production of one thing within each claim. Servier argued that the best method requirement is a subset of sufficiency and therefore was satisfied because there was no challenge to the patent in relation to sufficiency. The Court, however, found that the sufficiency and best method obligations are separate requirements reasoning that if additional information regarding the best method is not included in a specification it could place the patentee in an advantageous commercial position, relative to competitors, for example when the patent expires.

Servier also argued that the best method requirement was satisfied simply by the identification of the claimed compound and that a best method of producing perindopril arginine was not essential. The Full Court disagreed citing the nature of the invention, namely the increased storage ability of perindopril arginine, which the experts on both sides agreed could vary depending on the nature of the salt formed – that being method dependent. Thus, the Court found that there is an obligation on the patentee to provide the best method for producing a form of perindopril arginine that would best fulfil the promise of the invention.

The Court also reasoned that disclosure of the 1986 or 1991 methods would have saved the skilled addressee from possible “dead ends and false starts” risked in attempting to make the salt by “a classical method of salification” as disclosed in the patent. Thus, the Full Court dismissed Servier’s appeal and found that Servier had failed to describe the best method known to it of performing the invention.

Amendment of the patent

Following the initial Federal Court decision in relation to best method, Servier sought to amend the patent to introduce the 1986 and 1991 methods of making perindopril arginine. The allowance of such an amendment is at the discretion of the Court and the primary Judge exercised this discretion against Servier and refused to allow the amendment.

The salient issue considered by the Full Court in relation to whether the proposed amendment should be allowed was the content of correspondence between Servier and their Australian patent attorney during prosecution of the application. Specifically, Servier’s patent attorney made a recommendation to Servier to include a method for the manufacture of perindopril arginine, even if the method was well known in the art, so as to satisfy the written description requirement. In response, Servier expressed concerns because the method was confidential and did not heed their patent attorney’s advice.

The Full Court held that Servier erred in forming the view that the proposed amendment was unnecessary and that Servier’s decision to ignore the advice of their Australian patent attorney was not reasonable. Accordingly, the Full Court refused the application to amend the patent.

Conclusions

This Full Court decision clearly puts Australian patentees on notice to include the best method known to them of performing an invention. It will also, no doubt, motivate patent litigators to seek discovery in relation to methods known by a patentee but not included in a patent specification.

Servier has applied for special leave to appeal the Full Court decision to the High Court and Shelston IP will keep you promptly informed of developments

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